Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-08-03
2003-02-18
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S504000, C430S567000, C430S570000, C430S572000, C430S574000, C430S581000, C430S585000, C430S583000
Reexamination Certificate
active
06521401
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a spectrally sensitized silver halide photographic material.
BACKGROUND OF THE INVENTION
A great effort has been expended for increasing the sensitivity of silver halide photographic materials. It is thought that the transmission efficiency of light energy to silver halide is improved by increasing the light absorption rate of the dye for use in spectral sensitization of silver halide, as a result, the improvement of spectral sensitivity can be attained.
However, there is a limit to the adsorption amount of a sensitizing dye onto the surface of a silver halide grain. Ordinary sensitizing dyes are adsorbed onto silver halide grains in almost closest packing by a monolayer, therefore, it is difficult to make adsorb onto a silver halide grain the dye chromophore of the amount more than the monolayer saturation adsorption (i.e., the adsorption by a single layer) completely covering the surfaces of a silver halide grain. That is, even if sensitizing dyes of the amount more than the amount of the monolayer saturation adsorption is added, it means the mere increase of non-adsorbed dyes. Therefore, in the present situation, the absorption rate of the incident light quantum of each silver halide grain in the spectral sensitization region is still low.
The means suggested to solve these problems will be described below.
P. B. Gilman, Jr. et al. made a cationic dye adsorb onto the first layer and an anionic dye onto the second layer by electrostatic force as described in
Photographic Science and Engineering,
Vol. 20, No. 3, page 97 (1976).
G. B. Bird et al. made a plurality of dyes multilayer-adsorb onto silver halide to effect sensitization by virtue of the transfer of Forster type excitation energy as disclosed in U.S. Pat. No. 3,622,316.
Sugimoto et al. performed spectral sensitization by energy transfer from a luminescent dye as disclosed in JP-A-63-138341 and JP-A-64-84244 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”).
R. Steiger et al. tried spectral sensitization by energy transfer from a gelatin-substituted cyanine dye as described in
Photographic Science and Engineering,
Vol. 27, No. 2, page 59 (1983).
Ikekawa et al. performed spectral sensitization by energy transfer from a cyclodextrin-substituted dye as disclosed in JP-A-61-251842.
So-called connecting dyes having two chromophores which are not conjugated separately and connected by a covalent bond are disclosed in U.S. Pat. Nos. 2,393,351, 2,425,772, 2,518,732, 2,521,944, 2,592,196 and European Patent 565083. However, these dyes were not dyes aiming at the improvement of light absorption rate. As the dyes aiming at the improvement of light absorption rate actively, G. B. Bird, A. L. Borror et al. made connecting type sensitizing dye molecules having a plurality of cyanine chromophores adsorb onto silver halide to heighten the light absorption rate and contrived sensitization by the contribution of energy transfer as disclosed in U.S. Pat. Nos. 3,622,317 and 3,976,493 Ukai, Okazaki and Sugimoto proposed in JP-A-64-91134 to connect at least one substantially non-adsorptive cyanine, merocyanine or hemicyanine dye containing at least two sulfo groups and/or carboxyl groups to a spectral sensitizing dye adsorbable onto silver halide.
L. C. Vishwakarma disclosed in JP-A-6-57235 a method of synthesizing a connecting dye by a dehydration condensation reaction of two dyes. Further, L. C. Vishwakarma showed in JP-A-6-27578 that a connecting dye comprising monomethine cyanine and pentamethine oxonol had red-sensitivity, but in this case spectral sensitization due to Forster type excitation energy transfer between dyes was not effected because the luminescence of the oxonol dye did not overlap with the absorption of the cyanine dye. Therefore, higher sensitization by the light converging function of the connected oxonol cannot be obtained.
R. L. Parton et al. suggested a connecting dye having a specific linking group in EP-A-887770.
M. R. Roberts et al. suggested spectral sensitization by a cyanine dye polymer in U.S. Pat. No. 4,950,587.
As described above, numerous examinations have been conducted heretofore for the improvement of light absorption rate, but none of them was satisfactory in higher sensitization effect and there remained such problems as the increase of intrinsic desensitization and development inhibition.
In a color photographic material, in particular, it is necessary to make spectral sensitivity stay within an objective wavelength region. In spectral sensitization of a silver halide photographic material, J-band which is formed when a sensitizing dye is adsorbed onto a silver halide grain surface, is generally utilized without the use of the absorption of a sensitizing dye in a monomer state. Since J-band of a sensitizing dye has sharper absorption band shifted to the long wavelength side more than that in a monomer state, it is very useful to make a light absorption band and a spectral sensitivity band stay in the desired wavelength region. Hence, even if the light absorption rate can be increased by multilayer-adsorption of a sensitizing dye onto a grain surface, when the dye of the layers on and after the second layer which is not directly adsorbed onto the silver halide grain is adsorbed in the state of a monomer, a very broad absorption band is brought about, which is inappropriate as the spectral sensitivity of a practical photographic material.
On the other hand, each color sensitivity region has the width of about 100 nm, and it is not preferred for each light in that range to generate unnecessarily large sensitivity difference. Therefore, the techniques for increasing the strength of a light absorbing area per unit surface area of a silver halide grain by the multilayer-adsorption of a sensitizing dye onto the silver halide grain surface with limiting the absorption and spectral sensitivity to the desired width of color sensitivity region and still with making spectral absorption rate and sensitivity change of the light in the same range as small as possible have been desired.
It has been found that when a sensitizing dye is multilayer-adsorbed onto the surface of a silver halide grain, the adsorption amount of gelatin decreases and the property of protective colloid lowers, hence the agglomeration of particles is liable to occur sometimes. Therefore, the techniques of multilayer-adsorbing a sensitizing dye onto a silver halide grain and at the same time suppressing the agglomeration of grains has been demanded.
As a result of eager investigation to adsorb one or more layers of dye chromophores onto a silver halide grain, the present inventors have already found that one or more layers of dye chromophores can be adsorbed onto a silver halide grain by various methods, e.g., the method of using a dye having an aromatic group or a cationic dye having an aromatic group with an anionic dye in combination as disclosed in JP-A-10-239789, JP-A-8-269009, JP-A-10-123650 and JP-A-8-328189; the method of using a dye having poly-electric charges as disclosed in JP-A-10-171058; the method of using a dye having a pyridinium group as disclosed in JP-A-10-104774; the method of using a dye having a hydrophobic group as disclosed in JP-A-10-186559; and the method of using a dye having a coordinate bonding group as disclosed in JP-A-10-107980.
However, the sensitizing dyes for use in these methods are dyes having limiting structures, therefore, it is desired for higher sensitization to widen these techniques to make multilayer adsorption possible even with the dyes having the structures other than the structures of these dyes.
SUMMARY OF THE INVENTION
The objects of the present invention are to provide a high speed silver halide photographic material where agglomeration of grains is inhibited, to provide a silver halide emulsion for use therefor, and to provide a sensitizing dye necessary therefor.
According to the present invention, the multilayer adsorption structure of a dye can also be formed by using a betaine dye as
Kobayashi Katsumi
Yamashita Katsuhiro
Fuji Photo Film Co. , Ltd.
Letscher Geraldine
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